Overcoming Nevada Soil Limitations
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Overcoming Productive Limitations in Nevada’s Soils: the importance of pH, salts and organic matter
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Overcoming Nevada Soil Limitations
- 1. Overcoming the productive limitation of Nevada’s soils: the importance of pH, salts, and organic matter David Howlett, Ph.D. Nevada Division of Forestry July 17, 2013 UNCE
- 2. overview 1. good and bad soils 2. soil-related limitations to production 3. low organic matter 4. high pH 5. salts 6. tools to help you overcome these limits (web soil survey demo)
- 5. soil formation: the five soil forming factors Hans Jenny, 1949 1. parent material (metamorphic, volcanic, sedimentary) 2. topography/landscape (hill or bottom) 3. climate (47°, 8-9 in rain) 4. organisms (including us) 5. time (varied) Reno- Sparks area what factors can we control???
- 6. soil services • nutrient storage and delivery system for plants (food, fuel, and fiber) • storm water control, pollutant storage • structural support for roads and buildings
- 7. soil texture, or particle size distribution Soil Fraction Size, mm Feel in hand Surface area, cm3/g Sand <0.05- 2 gritty 21-210 Silt 0.02-0.05 smooth, silky 2,100 Clay <0.02 sticky 23,000 soil chemistry dominated by clay Why? surface area!
- 8. the soil solution • all nutrient uptake by plants occurs in aqueous solution (water is solvent) • charge matters! uptake mechanisms: mass flow, diffusion, and interception
- 9. soil characteristics that limit production 1. low organic matter 2. high salt content 3. high pH others… texture (distribution of particle sizes) depth to bedrock structure (erosion) hardpans compaction disturbance (mining, urban) toxicity (spills, mining, natural) high water table
- 10. 1. organic matter in the soil • nutrient reservoir (fertilizer use enhanced) • helps with structure • increases soil organisms • improves moisture status • helps prevent erosion • moderates soil temp • ~0-4% in N Nevada
- 11. organic matter diagnostics • soil color, darker the better • plants, duff layer presence indicator • soil test
- 12. how to increase organic matter? • add well-decomposed compost • grow cover crop or other plants, mix in • anything that helps plants grow will increase OM (irrigation, fertilizer, mulch) • combine with aeration treatments in turf
- 13. 2. soil pH or acidity • concentration of H+ and OH- ions in solution • expressed in log scale: pH 7 is 100 times more acidic than pH 9 major role in determining soil nutrient status…
- 14. pH and soil nutrient availability
- 15. What can you do about pH? • test pH- easy and cheap !! • lower pH with acidic material (S, or OM), watch for free carbonates (buffer) • grow plants tolerant to high pH
- 16. 3. accumulation of salts Source: http://www.fusion360inc.com/sections/benefits/FusionGallery >2,900 ppm Na Cl Fallon NAS
- 17. how does salt accumulate? •occurs naturally in ‘playas,’ dry lake bed •irrigation water contains salts that remain after water evaporates •poor drainage exacerbates
- 18. effects of high salt on soil? • salts reduce water uptake by plants • sodium (Na+) competes with other cations for exchange sites, disperses clay • reduced soil structure = lower infiltration, crusting on surface
- 19. how to deal with salt • on newly developed site, leach with irrigation (needs good drainage, check with probe)
- 20. how to deal with salt II • gypsum application, CaSO4 .2H2O (Ca replaces Na, difficult, must be repeated) • plant salt-adapted plants (talk to expert, UNCE publication 12-04) http://www.unce.unr.edu/publications/files/ho/2012/sp1204.pdf • maintain, improve drainage (install pipes, French drain, etc.)
- 21. soil test! • Chemical extraction of soils • Provides information on ‘plant available’ nutrients, salts, pH • Helps determine what your soil needs, or does not need to be productive does NOT test: pesticides, toxics, soil biology, total available nutrients Soil testing labs: http://www.growyourownnevada.com/resourc es/private-soil-testing-labs/
- 22. tools to help you • good observation, above and below ground • local nursery staff, UNCE • soil tests! • USDA Soil series web soil survey
- 23. review limitation diagnosis remedy caveat low organic matter light colored soil add OM, grow plants well- decomposed high pH test lower pH, amend, plant adapted species difficult to do on large scale, with free carbonates very hard high salts Crusting, plant symptoms (similar to water stress) Leach, amend, plant adapted species must have good drainage, keep up amendments
- 24. thank you! David Howlett, PhD Urban and Community Forester Nevada Division of Forestry (775) 684-2506 dhowlett@forestry.nv.gov http://forestry.nv.gov/
Notes de l'éditeur
- Brief overview of limitations on soils for production in NVNot detailed talk on soil chemical properties- no lab talkTalk geared for urban, not rural or agricultural
- Dark color- high OMPenetration of roots- low compactionGood growth- nutrients status highMaintain high water status
- We can still produce in difficult soil conditions, UNR, Fallon
- This tells you what you can and cannot change
- Limit benefits from previous slide
- Soil orgs help increase soil nutrients to plants
- Irrigation water holds salts and when applied, salts precipitate out